def test_starting_from(self):
graph = lil_matrix((3, 3), dtype='bool')
graph[1, 2] = True
longest_path = longest_path_in_tree(graph, 0)
self.assertArraysEqual(longest_path, np.array([0]))
longest_path = longest_path_in_tree(graph, 1)
self.assertArraysEqualOrReversed(longest_path, np.array([1, 2]))
def test_complex_tree(self):
'''
Network topology:
0 -> 2 -> 5 -> 8
| |
v v
1 4 -> 7 -> 9
| |
v v
3 6
'''
graph = lil_matrix((10, 10), dtype='bool')
edges = [(0, 1), (1, 3), (0, 2), (2, 4), (4, 6), (4, 7), (7, 9),
(2, 5), (5, 8)]
for source, target in edges:
graph[source, target] = True
longest_path = longest_path_in_tree(graph)
self.assertArraysEqualOrReversed(longest_path,
np.array([3, 1, 0, 2, 4, 7, 9]))
# Now move node 9 to be under node 8, instead of node 7. The path
# should change accordingly.
graph[7, 9] = False
graph[8, 9] = True
longest_path = longest_path_in_tree(graph)
self.assertArraysEqualOrReversed(longest_path,
np.array([3, 1, 0, 2, 5, 8, 9]))
def test_linear_tree(self):
graph = lil_matrix((5, 5), dtype='bool')
for i in range(4):
graph[i, i + 1] = True
longest_path = longest_path_in_tree(graph)
# Either order for the path is technically OK.
self.assertArraysEqualOrReversed(longest_path,
np.array([0, 1, 2, 3, 4]))
def test_single_node(self):
graph = lil_matrix((1, 1), dtype='bool')
longest_path = longest_path_in_tree(graph)
self.assertArraysEqual(longest_path, np.array([0]))